Electra Sailplane Conversion

[rockyboy]

I picked up a Goldberg Electra Sailplane from a local hobby shop that was closing down this summer. The builder did a great job with this plane - straight and true without a wrinkle anywhere!

It has the original designer recommended speed 400 brushless motor and speed controller - a rather chunky 9 ounces up front that combined with the mid 80s NiCad battery packs contributed to this plane being rather heavy and having a reputation for not so great performance.

So I'm going to replace that power system with a modern brushless Eflite 450 that should swing the same prop quite nicely at only 3.7 ounces. And the Lipo will be lighter than the old battery too, so overall it should be 7 or 8 ounces lighter.

Since the existing firewall holes are in all the wrong spots, I cut and drilled a new firewall.

Good old Titebond and a clamp works to glue the new firewall right onto the old one.

And now there's a brushless motor up front!

Yes, mounting this way will let the motor hang out and be visible.... Unless I can find some sort of cowling tube or spacer.... Not that excited about trying to find a brushless motor I could mount behind the firewall when I have this one sitting in my drawer already.

Next up - put the prop back on and do a balancing act!

 

[TooJung2Die]

This will be interesting. That Electra motor looks a lot like the DC motor that came with the Apollo sailplane I put together over a year ago. It was an old electric kit. I upgraded the electronics like you're doing. The new electronics weighed less than half of the original equipment. I bought the biggest Lipo batteries that would fit in the nose for ballast. I put the motor behind the firewall.

In the end I had to add another half pound of lead to the nose to achieve the CG. The final weight was the same as if I had the original motor and electronics in it. The glider was built to balance with the old heavy electronics. I can't complain though, it flies awesome.

So sticking the new motor way out front like that will be an advantage balance-wise. You're lengthening the nose and putting the motor weight further out front. You won't have to add as much ballast to get the CG right.

 

[rockyboy]

Wow - you were right on with predicting the ballast problem! When I've planned well enough ahead of time (like with my Dreamer biplane) I extended the whole nose of the aircraft forward to help with this. I think the Dreamer looks better this way, but on some designs that could be a bit ugly....

Back on the Electra I installed my favorite hatch latch and dialed in the radio so she's ready to launch.

I had to add an ounce and a half of lead in the front, so all ready to fly the weight reduction is only about 2.5 ounces (assuming she's not tail heavy still).

If she is, I'm going to try moving the servos further forward instead of adding more weights - they are a good 6" behind the CG now and since the battery is up front they could easily go right under the CG.

 

[speedbirdted]

My Gentle Lady I built in February needed 4 ounces in the nose to get it to balance right. I thought I could get it under 20 ounces by using better electronics but the associated CG problems pretty much killed any hope of that working. I think it came out at about 23 ounces, but the weight on the plans says 27-30 ounces so I guess it's still a little better. It still flies really good though. There are not many thermals out there now that it's a constant 45 degrees but I still managed an hour flight a few days ago.

I'm very tempted to build another one. I could probably get it to be a lot lighter with better wood. I'd also like to do a better job building it, as on the one I have I goofed in a few areas Anyway I'm eager to see this done. No way it'll disappoint!

 

[TooJung2Die]

It's often surprising to me how far back the CG should be on gliders.

 

[TEAJR66]

I'll be doing this to a Great planes Spectra, soon.

 

[rockyboy]

I'll be doing this to a Great planes Spectra, soon.

View attachment 181700

Awesome! I hope we get a build thread!

Are you planning to build pretty much stock or thinking about modifications already?

 

[TEAJR66]

Awesome! I hope we get a build thread!

Are you planning to build pretty much stock or thinking about modifications already?

Mods. It is going to be lighted. Trying to decide on the brushless out runner.

Won't be much of a build thread. But I will post progress occasionally.

 

[rockyboy]

Oooo.... lighting! Love the idea of a nice lighted electrocuted glider... I need another lighted flyer too... don't really want to peel the covering on this one though...

 

[speedbirdted]

If I ever build another Gentle Lady I'm tempted to try building EL wire into the wings and tail. Hopefully if I can cut out enough weight it won't add any extra.

 

[rockyboy]

She flys! Pretty darn well too - but to get her to balance out right I have a total of 1.5oz of lead in the nose.

Total all up flying weight is 33.5 oz which is still a good bit less than the 48 oz specified on the plans. I can see why people might not have liked it back in the day so much - with another 15 ounces this would be much less of a glider.

 

[rockyboy]

After less than a dozen flights, I had her at the field on Sunday when a new club member started asking me about gliders.

This person had been flying an Apprentice for a while and was looking to get a glider for his second plane. So I showed him the Electra and how it handled in the air.

He did the "ohhh... that's so pretty" as it silently slid past with the motor off.

So I told him to take it home.

He has a new plane, and I have space to build another one!

 

[TEAJR66]

I have made little progress on the Spectra. Zero documentation and i am not going to light this one up. I will wait for a bigger plane with a more substantial tail section to light up.

Way to go with the Electra. I'm sure its new owner will give it a lovely home.

Have you decided what the next build will be?

 

[rockyboy]

I have made little progress on the Spectra. Zero documentation and i am not going to light this one up. I will wait for a bigger plane with a more substantial tail section to light up.

Way to go with the Electra. I'm sure its new owner will give it a lovely home.

Have you decided what the next build will be?

Thanks!

Yeah, getting lighting into skinny tails is a challenge. Sort of stalled out on getting lighting into the tail - and trying to keep the tail removable on my Lazy Bee build over here: https://forum.flitetest.com/index.php?threads/lazy-bee-2020.65397/

 

[GliderFlyer]

I like how the fuselage tapers to match the spinner. I hope I can achieve that look in in my Olympic II.

 

[SEMO John]

I picked up a Goldberg Electra Sailplane from a local hobby shop that was closing down this summer. The builder did a great job with this plane - straight and true without a wrinkle anywhere!

going to replace that power system with a modern brushless Eflite 450 that should swing the same prop quite nicely at only 3.7 ounces. And the Lipo will be lighter than the old battery too, so overall it should be 7 or 8 ounces lighter.

Hi rockyboy,

I'm trying to electrify a Gentle Lady and your Electra conversion should be comparable. I've looked on Hobby King for an Eflite 450 and just come up with batteries. I did find a 920kv motor. Can you tell me what you ordered?

Thanks!

John

 

[SEMO John]

Hi rockyboy,

I'm trying to electrify a Gentle Lady and your Electra conversion should be comparable. I've looked on Hobby King for an Eflite 450 and just come up with batteries. I did find a 920kv motor. Can you tell me what you ordered?

Thanks!

John

NM. I just realized I was looking on 'Hobby King' for a 'Horizon Hobby' product. Google Is Your Friend! Sigh . . . .

John

 

[Piotrsko]

Just because it's heavy, don't mean it's not a good glider. It just wont turn in those teensy mini thermals.

Just so you know, my full size 86 span olympic has 16 ounces lead poured into the nose block then had 2 sticks of tire weights stuck on outside, but I beat the duration pro at CSUDH back in the day.

 

[Piotrsko]

There you be.